The IIsx is the world’s most popular 2-place, portable intercom. The modular design offers expansion capability to the backseat if needed. Expandable to 4-place portable with optional SR-4 expansion module Auxiliary inputs and outputs for music or recording flight information Low-battery indicator and pilot isolate Uses aircraft power or 9-volt battery Flightcom IISX 4 place includes: • All parts in the 2 place • SR-4 expansion module Specifications Weight: 10.5 oz Length: 4-1/4" Width: 2-3/6" Height: 2-5/16" Two-year Warranty